The Group for Research in Adult Acute Lymphoblastic Leukemia (GRAALL)-2014 trial (ClinicalTrials.gov: NCT02617004, NCT02619630) evaluated an intensive, age-adapted protocol for adults aged 18-59 years with Philadelphia chromosome-negative acute lymphoblastic leukemia (ALL). The trial was motivated by findings from the previous GRAALL-2005 study, which reported excessive toxicity from pediatric-inspired therapy in older patients and no added benefit from allogeneic hematopoietic stem cell transplantation (alloHSCT) in those with an early favorable response to treatment. Thus, the GRAALL-2014 protocol aimed to reduce treatment-related toxicity in patients aged ≥45 years and to limit alloHSCT to patients with poor measurable residual disease (MRD) responses. A total of 743 patients was included, and outcomes were compared to those of the GRAALL-2005 trial. The GRAALL-2014 demonstrated reduced early mortality and higher complete remission rates in patients aged ≥45 years. MRD-guided transplant decisions reduced alloHSCT indications by approximately 50%. While older patients experienced a higher cumulative incidence of relapse, no significant difference in disease-free survival (DFS) was observed compared to historical cohorts across age subgroups. The overall 4-year DFS was 57.1% (95% CI, 53.4-61.1). Notably, 4-year overall survival improved significantly, from 65.5% (95%CI, 61.7-69.8) to 71.7% (95%CI, 67.7-76.0) in younger patients (p=0.031) and from 49.6% (95%CI, 43.5-56.5) to 59.5% (95%CI, 53.5-66.3) in older patients (p=0.011). These findings highlight the value of individualized treatment strategies, balancing efficacy and safety. Future studies should investigate the integration of immunotherapy to further reduce treatment intensity and improve outcomes.

The repair of pathological gene variants is an ultimate aim for treating genetic diseases; however, the development of different therapeutic reagents for each of the many variants that can occur in a gene may not be scalable. Here, we investigated whether base editing to introduce a gain-of-function variant in blood coagulation factor IX (FIX) can increase FIX activity as a targeted therapeutic approach for hemophilia B. We engineered a G:C to A:T substitution at c.1151 of F9 by cytosine base editing to generate R338Q, known as the Shanghai F9 variant, which markedly potentiates coagulation factor activity. An adeno-associated virus vector harboring the base editor converted more than 60% of the target G:C to A:T and increased FIX activity in HEK293 cells harboring patient-derived F9 variants, as well as in knock-in mice harboring a human F9 cDNA. Furthermore, administration of lipid nanoparticles embedded with the base editor mRNA and gRNA increased FIX activity in mice. These data indicate that cytosine base editing to generate R338Q in FIX is a broadly applicable genome editing approach for hemophilia B with residual FIX activity.

GPRC5D has emerged as a promising therapeutic target in relapsed/refractory multiple myeloma (RRMM), particularly following progression after BCMA-directed CAR T-cell therapies. RD118 is a novel CAR T-cell therapy incorporating a fully human single-domain antibody fragment (VHH) targeting GPRC5D. In this phase 1 study, 18 relapsed/refractory patients (17 multiple myeloma, 1 with a history of primary plasma cell leukemia [pPCL]) received a single infusion of RD118 at 1.0, 2.0, or 3.0 × 106 CAR+ T cells/kg. At a median follow-up of 17.0 months, the overall response rate (ORR) was 94.4%, including 72.2% complete or stringent complete responses. Among seven patients previously exposed to BCMA-directed CAR T-cell therapy, ORR reached 85.7%. Median progression-free survival (PFS) was 18.2 months (95% CI, 14.4-not estimable), with 12-month PFS and overall survival (OS) rates of 82.1% and 93.3%, respectively. Cytokine release syndrome occurred in 88.9% of patients, primarily grade 1-2. One patient developed grade 3 immune effector cell-associated neurotoxicity which resolved within 72 hours. No cerebellar toxicities or treatment-related deaths were reported. These findings support that RD118 is a highly effective and safe therapeutic option for heavily pretreated RRMM. This trial is registered at ClinicalTrials.gov as NCT05759793 and NCT05219721.

Myeloid leukemia in children with Down Syndrome (ML-DS) is associated with an excellent prognosis but high treatment-related toxicity and mortality. The ML-DS 2018 trial aimed to maintain the excellent event-free survival achieved in the previous ML-DS 2006 trial while further reducing treatment intensity. Children aged 6 months to 6 years with ML-DS were eligible. Intensity-reduced induction and reinduction therapy with cytarabine, idarubicin ± etoposide of the ML-DS 2006 trial was replaced with CPX-351 (66 U/m² on three days in course 1 and two days in course 2). Risk stratification was based on flow cytometric measurable residual disease after first induction. High-risk patients received high-dose cytarabine (3 g/m²/12h) in consolidation; standard-risk patients received 1 g/m²/12h. Thirty-five patients were enrolled until the trial was halted due to an unexpectedly high relapse rate. A per protocol interim analysis revealed a significantly lower 24-month event-free survival compared to the ML-DS 2006 trial (69% vs. 90%, P<.001). In contrast to previous studies, most relapsed patients responded to salvage therapy, resulting in a comparable 24-month overall survival of 88% (vs. 92% in ML-DS 2006, P=.612). CPX-351 demonstrated a favorable toxicity profile with no treatment-related mortality. Positive measurable residual disease by error-corrected GATA1 next-generation sequencing, as well as the presence of trisomy 8 or a complex karyotype, were associated with an increased risk of relapse. In conclusion, replacing intensity-reduced induction therapy with CPX-351 in ML-DS resulted in significantly lower event-free survival, highlighting the need for dose optimization to balance efficacy and toxicity in this sensitive patient population. EudraCT: 2018-002988-25.

Oncogenic growth places great strain and dependence on protein homeostasis (proteostasis). This has made proteostasis pathways attractive therapeutic targets in cancer, but efforts to drug these pathways have yielded disappointing clinical outcomes. One exception is proteasome inhibitors, which are approved for frontline treatment of multiple myeloma. However, proteasome inhibitors are largely ineffective for treatment of other cancers at tolerable doses, including acute myeloid leukemia (AML), although reasons for these differences are unknown. Here, we determined that proteasome inhibitors are ineffective in AML due to inability to disrupt proteostasis. In response to proteasome inhibition, AML cells activated HSF1 and increased autophagic flux to preserve proteostasis. Genetic inactivation of HSF1 sensitized AML cells to proteasome inhibition, marked by accumulation of unfolded protein, activation of the PERK-mediated integrated stress response, severe reductions in protein synthesis, proliferation and cell survival and significant slowing of disease progression and extension of survival in vivo. Similarly, combined autophagy and proteasome inhibition suppressed proliferation, synergistically killed human AML cells, and significantly reduced AML burden and extended survival in vivo. Furthermore, autophagy and proteasome inhibition preferentially suppressed protein synthesis and colony formation, and induced apoptosis in primary patient AML cells, including AML stem/progenitor cells, compared to normal hematopoietic stem/progenitor cells. Combined autophagy/proteasome inhibition activated a terminal integrated stress response, which was surprisingly driven by Protein kinase R (PKR). These studies unravel how proteostasis pathways are co-opted to promote AML growth, progression and drug resistance, and reveal that disabling the proteostasis network is a promising strategy to therapeutically target AML.

Acute myeloid leukemia (AML) is a polyclonal malignancy marked by high relapse rates despite initial morphologic remission. Although measurable residual disease (MRD) is an established prognostic tool, increasing evidence supports a role for pre-emptive, MRD-directed therapy. AML monitoring is hampered by absence of a universal MRD marker, necessitating a more personalized approach. NPM1 is suited to an MRD-directed strategy as the mutation is AML-defining and monitoring methods highly sensitive. Critically, rising NPM1mut levels portend clinical relapse with high fidelity and recent studies demonstrate that venetoclax-based regimens induce rapid and deep MRD responses in a high proportion of patients with NPM1mut MRD relapse. The range of MRD-directed treatment options are expanding and include FLT3 and menin inhibitors for MRD relapse driven by FLT3-ITD and KMT2A rearrangements, respectively. To overcome the logistical issue of multiple MRD markers and associated therapies, we have developed a multi-target, multi-arm platform trial named INTERCEPT. Novel features include the potential to adaptively expand the range of MRD markers and directed therapies, seamless transition of patients from a local to centralized MRD monitoring framework, a clinical decision rules approach to allocate treatment in a hierarchical and pre-specified manner, creation of parallel protocol appendices to enable multiple industry partners to co-exist with commercial independence, and development of approaches to minimize the "MRD relapse to treatment" time interval. The future success of MRD-directed therapy will depend on rapid diagnostic turnaround, coordinated logistics and innovative clinical trial designs able to keep pace with advances in MRD-detection technologies and associated targeted therapies.

The BCR::ABL1 tyrosine kinase inhibitors (TKIs) in CML represent a paradigm for molecularly targeted therapy. However, clinical outcomes - rate/depth of response, treatment-free remission (TFR), progression to blast crisis (BC) - and adverse events vary among patients. While additional somatic mutations have been invoked to explain varying clinical outcomes, we here propose a complementary perspective based on single-cell omics approaches that have enabled unprecedented resolution of the cellular ecosystems, including their composition, interactions, and activity. In treatment-naïve chronic phase (CP) patients, this has revealed differences in the growth-rate of BCR::ABL1+ clones, ratio of TKI-insensitive leukemic stem cells (LSCs) to residual hematopoietic stem cells (HSCs), and immune cell composition - factors that collectively contribute to variability in therapy efficacy. Together these findings suggest that cellular heterogeneity serves as a foundation of clinical outcome in CML. Patients who remain in CP exhibit an erythroid signature in LSCs, while those progressing to BC manifest an inflammatory profile, additional mutations, and expansion of early progenitors. Deep responders with active natural killer, and regulatory T-cells are more likely to sustain TFR. Similarly, the outcomes of donor lymphocyte infusion after allogenic stem cell transplantation are heterogenous and reflect differences in pre-existing T-cell clonotypes, their expansion and interaction with leukemic cells in responders versus non-responders. Here, we summarize key insights from sc-omics in CML and propose an actionable roadmap to further leverage these technologies. This includes mechanistically explaining heterogeneity, predicting therapy response and BC, tracking leukemogenic clones longitudinally, targeting TKI-insensitive LSCs, and restoring hematopoiesis from residual HSCs.

The European LeukemiaNet has periodically issued guidelines for the diagnosis and management of acute myeloid leukemia (AML) in adults. These consensus recommendations, most recently updated in 2022, incorporate recent advances in genomic testing, disease detection methods, target identification, and response assessment. Whilst similarities exist between AML in children and adults, pediatric AML is frequently characterized by unique cytogenetic and molecular features, which require distinct genetic and immunophenotypic diagnostics, therapeutic approaches, response assessment criteria, and supportive care strategies. To address these specific needs, an international panel of pediatric hematologist-oncologists, biologists, geneticists, and laboratory medicine scientists convened to develop recommendations for the diagnosis and management of AML in children, adolescents, and young adults (hereafter termed pediatric AML) that are discussed in this special report.

Epstein-Barr virus (EBV) infects over 90% of the global population and drives multiple aggressive B cell malignancies, including Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL), and Hodgkin lymphoma. Standard chemoimmunotherapy regimens can be highly effective, yet EBV-positive lymphomas sometimes exhibit poorer responses, higher resistance, and worse survival compared with EBV-negative counterparts. This reflects the virus's ability to drive immune evasion, alter cell death pathways, and exploit host immune dysfunction, underscoring the potential value of EBV-directed strategies. Withaferin A (WA), a steroidal lactone with known anti-cancer and anti-inflammatory properties, was evaluated for its efficacy against EBV-associated B cell non-Hodgkin lymphomas (B-NHLs). Across a panel of lymphoma cell lines, WA demonstrated selective cytotoxicity toward EBV-positive B-NHLs in part through proteasome-dependent degradation of EBV nuclear antigen 1 (EBNA1) and subsequent loss of viral episomes, alongside additional effects on cellular stress and survival pathways. Mechanistic studies revealed that WA collapses antioxidant defenses, drives oxidative stress, and suppresses NF-κB signaling, creating a multi-pronged disruption of viral and host survival pathways. In primary B cell models and a cord-blood humanized mouse model of EBV-driven lymphomagenesis, WA inhibited B cell transformation, reduced splenomegaly and tumor burden, and significantly prolonged survival, without evidence of increased viral replication. These findings establish WA as a potent preclinical candidate that selectively targets vulnerabilities unique to EBV-transformed B cells, supporting further optimization and evaluation for EBV-positive B cell malignancies.

The peptide hepcidin is produced by the liver and serves as the central negative regulator of iron trafficking. Recently, drugs that affect the hepcidin pathway have been evaluated as potential treatment options for both controlling the degree of erythrocytosis in polycythemia vera (PV) patients as well as correcting anemia associated with myelofibrosis (MF). Under normal conditions, increased hepcidin levels limit iron absorption from the gastrointestinal tract and iron recycling from liver and splenic macrophages, thus decreasing plasma iron levels and restricting iron availability for erythropoiesis. In PV, however, unrestricted erythropoiesis occurs despite low systemic iron levels. Since hepcidin levels are relatively low in PV patients, hepcidin agonists (rusfertide, divesiran, sapablursen) are undergoing clinical development to control PV associated erythrocytosis, thereby reducing the need for therapeutic phlebotomies and myelosuppressive therapeutic options. By contrast, hepcidin levels are increased in MF patients leading to the trapping of iron in tissue macrophages which creates a picture which resembles the anemia of chronic inflammation. A number of strategies to lower hepcidin levels (the JAK2 inhibitors pacritinib and momelotinib, anti-hemojuvelin monoclonal antibody DISC-0974C) are currently undergoing clinical development to make systemic iron available for erythropoiesis and alleviate the degree of MF associated anemia. These new therapeutic options that modulate iron trafficking in PV and MF patients represent the application of greater knowledge of iron trafficking to create novel therapeutic options to treat patients with hematological malignancies.

Tissue factor (TF), encoded by F3, binds factor VII/VIIa to initiate blood coagulation. Because standard clinical assays do not measure endogenous TF directly, the extent to which human F3 variants impact blood coagulation is unknown. We sought to determine the effect of the human TF missense variants with the highest allele frequency as well as additional rare variants occurring at sites predicted to perturb the initiation of blood coagulation. The variants with the highest allele frequency did not impact coagulation activation. By contrast, some rare human TF missense substitutions did profoundly impact TF-initiated plasma clotting time and the activation of factors IX and X by two distinct mechanisms: by precluding TF interaction with factor VIIa or by altering the TF exosite to prevent macromolecular but not amidolytic substrate cleavage. Individuals heterozygous for the rare p.Gly196Arg variant have reduced basal factor VIIa-antithrombin complex and D-dimer levels but no major differences in TF or factor VII levels. Gly196Arg supported impaired factor VII autoactivation in vitro. These data demonstrate that rare missense variants in F3 can impair the activation of factors VII, IX and X and suggest these variants impair the basal activation of blood coagulation in humans.

We describe the first case of NMNAT3 deficiency, a novel red cell enzymopathy leading to reduced NAD levels, causing mild hemolytic anemia which improved upon supplementation with NAD-precursors. We therefore propose testing for NMNAT3 variants in unexplained hereditary hemolytic anemia.

CD19 chimeric antigen receptor (CAR) T-cell therapy has become the standard of care in relapse and/or refractory B-cell malignancies. 30-60% of patients experience relapsed disease due to the emergence of CD19low or CD19negative tumor cell clones. Although bispecific CD19/CD22 CAR-T cells have been explored, limited persistence and antigen downregulation of CD19 and/or CD22 in relapsing patients have compromised their efficacy. A comprehensive analysis of CD22 expression revealed that CD22 is ubiquitously expressed across all subgroups of B-cell lymphomas and B-cell leukemias, establishing CD22 as a valuable immunotherapeutic target. Using a humanized mouse model with a diverse human TCR repertoire, we identified a high-affinity T-cell receptor (TCR) targeting a CD22 epitope presented by HLA-A*02:01. In-vitro, this TCR demonstrated high specificity and efficacy in both CD22-positive cell lines and primary patient-derived tumor samples. Importantly, CD22 TCR-T cells outperformed CD22 CAR-T cells in recognizing cells with low CD22 surface expression, including CD22low Nalm6 cells that emerged after in-vivo CD19 T cell treatment. Unlike CD22 CAR-T cells, CD22 TCR-T cells effectively recognized tumor cells that predominantly express intracellular CD22. Notably, in-vivo validation in a Nalm6 B-cell leukemia model confirmed the superior activity of CD22 TCR-T cells against CD22low cells compared to CD22 CAR-T cells. In conclusion, our findings provide strong preclinical evidence supporting CD22 TCR-based therapy as a potent treatment option for CD22low B-cell malignancies, including patients who relapsed following CD19 CAR-T therapy.

In multiple myeloma (MM), cell-specific antigens are valuable targets for developing effective T-cell-engaging therapeutics which could provide good immune responses. Achieving a sustained immune response in recurrent MM, however, remains challenging. Ramantamig (JNJ-79635322) is a trispecific antibody targeting B-cell maturation antigen (BCMA) and G-protein-coupled receptor class 5 member D (GPRC5D), both of which are highly expressed on plasmablasts and plasma cells in myeloma patient samples. Dual antigen recognition on malignant plasma cells by a trispecific T-cell engaging antibody could potentially enhance tumor binding through increased avidity, resulting in efficient depletion of the malignant clonal populations, targeting of tumor heterogeneity, and prevention of tumor antigen loss mediated resistance. At sub nM ranges, ramantamig induced potent cytotoxicity in cancer cell lines with concomitant T-cell activation. Ramantamig efficiently depleted both dual and single target-expressing MM cell lines. Additionally, it induced dose-dependent depletion of malignant plasma cells both in MM patient samples in an ex-vivo T-cell co-culture assay and in healthy fresh whole blood co-cultured with H929 MM cells to mimic physiological conditions. Ramantamig exhibited potent antitumor activity in a murine xenograft prevention model (single-target-expressing clonal cells) and two tumor regression models. The potent and selective antitumor activity of ramantamig, with a clonal depleting ability in vitro, ex vivo, and in vivo warrants clinical evaluation of its ability to induce durable responses in myeloma. Phase 1 clinical trials are ongoing for patients with relapsed/refractory MM (NCT05652335, NCT06768489).

Clinical trial eligibility criteria select a target population and reduce anticipated risks for participants but may unnecessarily limit participation both overall and differently across demographic groups. We previously abstracted eligibility criteria for 190 phase II/III acute myeloid leukemia (AML) trials and used Food and Drug Administration and professional society guidance on modernizing criteria to develop alternative, safety-based eligibility criteria for each trial. In this analysis, these trial- and safety-based eligibility criteria sets were applied to a retrospective cohort of 2226 newly-diagnosed patients across 8 hospitals to assess impacts on eligibility. Eligibility proportions increased from a median of 47.9% with trial-based criteria to 84.2% with safety-based criteria (median difference 30.0%; p<0.001); excluding age criteria, the increase was 11.5% (p<0.001). Non-Hispanic (NH)-Asian, NH-Black, NH-White, and Hispanic patients were eligible for median proportions of 41.1%, 44.0%, 47.9%, and 50.0% with trial-based criteria, increasing by 27.9-31.6% when using safety-based criteria (within group changes all p<0.001; between-group changes all p>0.05). Excluding age criteria, increases were between 10.0-11.9%. Moving from trial- to safety-based criteria decreased the proportion of trials with significant eligibility differences between NH-White and NH-Asian (-11.1%), NH-Black (-4.2%), and Hispanic (-12.1%) patients. Criteria significantly associated with increased eligibility and decreased between-group differences in eligibility were coronary artery disease, congestive heart failure, aspartate transaminase level, upper age limits, and prior malignancy. These data suggest that modernization of eligibility for AML trials to focus on safety-based criteria can improve both overall enrollment and population representation.

The transcription factor MECOM, located at 3q26, is essential for hematopoietic stem cells (HSCs) in healthy individuals. Enhancer translocations, due to 3q26 rearrangements, drive out-of-context MECOM expression in one of the most aggressive subtypes of acute myeloid leukemia (AML). Aberrantly expressed MECOM is essential for the survival and immature phenotype of these leukemia cells. Direct depletion of MECOM using an endogenous auxin-inducible degron immediately upregulates expression of CEBPA, encoding a transcription factor required for neutrophil development which is frequently mutated in other AML subtypes. MECOM depletion is accompanied by a severe loss of CD34 and gain of mature myeloid cell surface marker CD15. MECOM exerts its inhibitory effect on differentiation by binding to the +42kb CEBPA enhancer. This is partially dependent on the interaction between MECOM and its co-repressor CTBP2. We demonstrate that CEBPA overexpression can bypass the MECOM-mediated block of differentiation. In addition, AML patients with MECOM overexpression through enhancer hijacking show significantly reduced CEBPA levels. Our study directly connects two major players in normal and malignant hematopoiesis, MECOM and CEBPA, and unveils how MECOM maintains self-renewal by repressing CEBPA-induced differentiation.

Hematopoietic stem and progenitor cells (HSPC) are regulated by interactions with stromal cells in the bone marrow (BM) cavity, which can be segregated into two spatially defined central marrow (CM) and endosteal (Endo) compartments. However, the importance of this spatial compartmentalization for BM responses to complex conditions like inflammation remains largely unknown. Here, we extensively validate a combination of scRNA-seq profiling and matching flow cytometry isolation that reproducibly identifies 7 key CM and Endo populations and accurately surveys both niche locations. We demonstrate that inflammatory perturbations exert specific effects on different cellular compartments, with type I interferon responses causing leptin receptor-expressing mesenchymal stromal cells to abandon their normal stromal functions and instead adopt an inflammatory phenotype associated with overproduction of chemokines that modulate local monocyte dynamics in the surrounding microenvironment. Our results provide a comprehensive method for molecular and functional stromal characterization and highlight the importance of altered stomal cell activity in regulating hematopoietic responses to inflammatory challenges.

Circulating tumor cells (CTC) represent a high-risk biomarker in newly diagnosed multiple myeloma (NDMM); however, their prognostic value among transplant-eligible (TE) patients receiving daratumumab with bortezomib/lenalidomide/dexamethasone (D-VRd) remains unknown. Here, we analyzed CTC in the phase 3 PERSEUS trial (EMN017/NCT03710603). TE patients with NDMM were randomized (1:1) to D-VRd with daratumumab/lenalidomide maintenance (D-VRd group) or VRd with lenalidomide maintenance (VRd group), both with transplant. A subset of 451/709 patients from PERSEUS (D-VRd, 231/355; VRd, 220/354) had screening blood samples collected for CTC analysis by flow cytometry (median follow-up, 47.6 months). CTC were detected in 370/451 (82%) patients (median limit of detection, 0.0004%). CTC were prognostic of progression-free survival (PFS), independently of other factors, as a continuous (HR, 1.36 [95% CI, 1.15-1.60]; P<0.001) and categorical variable (≥0.175% CTC-high, optimal threshold). D-VRd improved PFS versus VRd in CTC-low patients (4-year rates: 88% vs 74%; HR, 0.42 [95% CI, 0.25-0.70]; P=0.0013). Regardless of study treatment, minimal residual disease (MRD)-negativity rates were lower in CTC-high versus CTC-low patients (10-5: 52.2% vs 66.2%; 10-6: 34.8% vs 52.4%). D-VRd significantly increased MRD-negativity rates versus VRd among CTC-high (10-5: 69.4% vs 33.3%; 10-6: 47.2% vs 21.2%; both P<0.05) and CTC-low patients (10-5: 74.4% vs 57.8%; 10-6: 65.6% vs 38.5%; both P<0.001), with similar observations for sustained MRD negativity. CTC levels are an independent prognostic factor in TE-NDMM patients treated with standard-of-care frontline quadruplet. D-VRd improved overall and sustained MRD-negativity rates in CTC-high and CTC-low patients, and improved PFS for CTC-low with a positive trend in CTC-high patients. NCT03710603.

Chronic graft-versus-host-disease (cGvHD) is the primary non-relapse limitation to a successful hematopoietic cell transplantation (HCT) and is largely treated as a single biological entity. We hypothesized that there exist different biological subtypes of cGvHD. Using the ABLE network database, derived from the largest pediatric cGvHD cohort worldwide, we applied clustering analysis to subtype cGvHD patients from the ABLE1.0 and 2.0 studies (51 cGvHD patients, 158 non-cGvHD patients). We found three distinct cGvHD subtypes: cGvHD-1 was characterized by an effector memory (TEM), cytotoxic NK cell, and early precursor B cell predominant pattern; cGvHD-2 was phosphatidylcholine, cytokine, and plasma cells predominant; and cGvHD-3 had more naïve CD4+ T cell (TN) and naïve Treg, had later onset, and the only subtype with measurable TREC. We partially replicated these subtypes using metabolomic data from a separate pediatric cohort of the COG trial ASCT0031 (33 cGvHD patients, 39 non-cGvHD patients). Further, cGvHD-1 was associated with serotherapy (predominantly ATG) exposure, and cGvHD-3 was associated with receiving peripheral blood stem cells (PBSC) from donors, total body irradiation (TBI), and no previous acute GvHD. cGvHD-2 was associated with liver involvement and cGvHD-2 and -3 with de novo cGvHD. Overall, none of the subtypes closely associated with organ involvement. Contrasting each subtype against non-cGvHD patients, the 3 subtypes shared common markers, all of which were used in our previous cGvHD diagnostic classifier. These findings suggest the presence of distinct biological subtypes of cGvHD that may help guide therapeutic strategies.

The primary objective in multiply-relapsed hairy cell leukemia and variant (HCL/HCLv) was to determine if pentostatin-rituximab (DCFR) and bendamustine-rituximab (BR) each have overall response rate (ORR) exceeding that historically achieved by rituximab alone (~40%) in favor of 65%. Prospective data was unreported for either regimen. Fifty-six patients received six 28-day cycles of rituximab (375 mg/m² days 1, 15) with either bendamustine (90 mg/m² days 1, 2) or pentostatin (4 mg/m² days 1, 15). Eligibility required ≥2 purine analogs, or one plus rituximab for initial response <1 year. Complete remission (CR) and minimal residual disease (MRD) were studied, and progression-free survival (PFS) with hazard ratios (HR) determined. Although patients were assigned to either regimen through randomization for increasing homogeneity of the two treatment groups, the DCFR arm had fewer prior purine analogs (p=0.021) and lower baseline marrow HCL/HCLv infiltration (p=0.013). ORRs for DCFR and BR were 93% and 86%, 95% confidence intervals (95%CI) 83-102% and 73-99%, each exceeding the primary objective (40% in favor of 65%, p<0.0001 for each). Rates for CR and MRD-free CR and median PFS (141 vs 50 months, HR 0.63, 95%CI 0.32-1.25) numerically favored DCFR but that arm was significantly enriched with lower prior purine analogs and marrow infiltration each of which was associated post hoc with better response. Post hoc subgroup analysis particularly for the 41 patients with classic HCL suggested any superiority of DCFR vs BR might apply to the more favorable patients. DCFR and BR were highly effective in multiply relapsed HCL/HCLv. Possible DCFR superiority was hypothesis-generating, given uneven baseline risks and trial design. NCT01059786.